Jason Lowe’s first Blackburn goal lifted Rovers into the top half as they picked up their first win in four.
The midfielder’s 76th minute strike lit up a dour match in which both sides struggled to create chances and keep possession.
But after ex-England u21 ‘keeper Jason Steele had made a trio of fine first-half saves, Lowe rifled a stunning 22-yard strike into the top corner to hand Gary Bowyer’s side the points.
And Bowyer said: “Credit to Jason Lowe. He works very hard to improve his game all the time and adding goals to it was part of his area for improvement.
“It’s not a bad way to open your account, is it?”
Steele first denied Alan Judge as he pushed a free-kick over the bar, before diving low to his left to tip a Jordan Rhodes header round the post.
And late in the first half, he palmed away a stinging effort from lively winger Josh King.
At the other end, Kai Kamara came closest with a header that was pushed away by Jake Kean, while Jonathan Woodgate fired off target.
Middlesbrough should have taken the lead on the hour when Albert Adomah failed to connect with Kamara’s cross.
And then Blackburn fans were left incensed by referee Carl Boyeson’s decision not to award a penalty after Matt Kilgallon was clattered by Woodgate.
But minutes later, their jeers became cheers as Lowe arrowed home to ease the tension around Ewood Park.
Middlesbrough piled forward after the goal, but failed to test Kean.
Their best chance fell to sub Lucas Jutkiewicz, who headed high and wide from close range, whilst Kamara saw another shot deflect off target.
Boro caretaker-manager Mark Venus said: “The players are disappointed. They didn’t lose the game through a lack of effort.
“It was a great goal.”